This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this protocol is to conduct a prospective, randomized study to compare efficacy and safety of two dose schedules of prednisone (0.75 mg/kg/day given daily and 10 mg/kg/week given in equal doses over two days) in boys with DMD. AIM 1: To compare efficacy of a daily prednisone dose of .75mg/kg with a weekly dose of 10 mg/kg split over two consecutive days. The primary efficacy measures will be quantitative muscle testing (QMT) scores of the upper and lower extremities, consisting of paired flexor/extensor groups. Secondary efficacy measures will include individual QMT scores of elbow and knee flexors and extensors and hand grip, manual muscle testing, timed function tests, pulmonary function tests and functional evaluation. Hypothesis: High dose prednisone (2X daily dose) given intermittently will be as effective as daily dose in slowing down the progress of muscle weakness in DMD. AIM 2: To compare side effect profiles between the two regimens, to include height, weight, weight/ height ratio, body mass index, bone density, cataract formation, blood glucose, blood pressure and behavioral changes. Hypothesis: High dose prednisone (2X daily dose) given intermittently will be less toxic and hence cause fewer side effects than daily dose therapy in DMD. CINRG Clinical Evaluator Reliability Training Objective: This training is being conducted to ensure inter-rater reliability of clinical evaluators performing manual muscle testing (MMT), QMT, and functional tests for the multicenter CINRG group. Specific Aims and Hypothesis: What is the inter-rater reliability of clinical evaluators at the Texas Children's Hospital CINRG site (relative to the "gold standard" clinical evaluators of this multicenter research group) for MMT, QMT, and functional testing of DMD subjects?base for the current randomized study.